Heretofore, as disclosed in Manning U.S. Pat. No. 4,021,073 and Fisher et al U.S. Pat. No. 4,329,917, ventilators for vehicle roofs have been proposed in which a closure member, lid, or panel for closing an opening in a vehicle roof, is connected to the roof by a plurality of link-and-spring assemblies which enable it to be opened to any of a plurality of positions and yieldably resist by the spring or springs of the assemblies movement of the closure member from closed or any open position. Of these patents, in Manning the springs of the connecting assemblies are each a coil spring in compression mounted in a tube fixed to the closure member and acting at opposite ends on plungers, each pivotally connected to one end of one of the links, the other end of which is pivotally connected to a mounting plate fixed to a frame bounding the opening in the roof. As opposed to Manning, Fisher et al pivotally mounts one end of each link and the compression coil spring in a box fixed to a frame bounding the roof opening and applies the force of the spring to the link through a ball contained in the box and alternately fittable in each of three sockets in the adjoining end of the link corresponding to full, partly open and closed positions of an adjoining side of the closure member. In both patents over-center relations between the pivot pins at opposite ends of each link in the open and closed positions of the adjoining side of the closure member, are designed to enable the associated spring to yieldably resist movement of the side out of those positions. It is to an improvement in vehicle ventilators such as disclosed in Manning and Fisher, that the present invention is primarily directed.